The invention can be applied to various types of quick couplings which have to withstand high pressure or pressure peaks. As an example, mention can be made of the quick coupling according to the U.S. Pat. No. 4,289,164 which has an insertion nipple which can be introduced into a female part and locked to the latter with the aid of locking members in the form of a number of locking balls. The insertion nipple constitutes a part of the male coupling part of the quick coupling, to which the insertion nipple can be fastened by means of joints, e.g. threaded joints, and sealed by means of seals. The insertion nipple must, among other things, be made with a hardness which withstands the high pressure and the safety standards associated therewith. Such standards require that the coupling has to withstand, in practice, pressure which is 3-4 times higher than nominal. This means that the insertion nipple of the high-pressure coupling is, in general, made with a hard surface layer and relatively large dimensions.